Because of the requirement in calculation, there have been calculators having common physical constants or physical astronomical constants built therein. Users can quickly call the value of a physical constant or a physical astronomical constant when performing calculation to save the time of looking up the physical constant or the physical astronomical constant.
In a calculator having physical constants or physical astronomical constants built therein, when a user wants to call the value of a constant, he must first input an item number of the constant stored in the calculator and then press an execution key (CONST key) for displaying the value of the constant on the screen of the calculator.
FIG. 1 shows an operation flowchart for inputting of a constant, which comprises the following steps:
Step 41: An item number of the constant is inputted;
Step 42: Whether the input of the item number is finished is determined. If the answer is yes, Step 43 is jumped to; otherwise, Step 41 is jumped back to;
Step 43: Whether the CONST key is pressed is determined. If the answer is yes, Step 44 is jumped to; otherwise, Step 46 is jumped to;
Step 44: Whether the inputted item number exceeds 136 (the total number of constants stored in the calculator) is determined. If the answer is yes, Step 47 is jumped to; otherwise, Step 45 is jumped to;
Step 45: The value of the constant is displayed;
Step 46: An arithmetic/logic unit is entered;
Step 47: The calculator displays an “ERROR” message.
For instance, if the item number of the speed of light in vacuum c in a calculator is 1, a user needs to first input 1 and then press the CONST key when he wants to call out the const of c. The value of c 299792458 will then be displayed on the screen of the calculator.
In the above input process, it is necessary for the user to know the item number of a constant in the calculator in advance. Usually, the item number of a constant can be looked up in an operation manual of the calculator or an index card attached. Therefore, the user needs to look up the operation manual or the index card when inputting a constant. The process is troublesome. Moreover, the calculator can only display the value or the representative symbol (e.g., c for the speed of light in vacuum) of a constant, but cannot display the unit of the constant or the real value of the constant in the calculator. Furthermore, if the operation manual or index card is lost, the user cannot accurately input constants.
Accordingly, the conventional calculator has inconvenience and drawbacks in the practical usage of constant input. The present invention aims to propose a calculating device capable of displaying constants and the method thereof to resolve the problems in the prior art.